Free Postmark alternative

There are roughly 25-35 viable transactional email tools competing in the free-or-cheap segment, but the market is stratified and fragmented rather than saturated. The real pain points aren't feature gaps—it's reliability anxiety (will my welcome emails actually land in inboxes?), deliverability transparency (most cheap tools hide their infrastructure details), and hidden overage costs that sneak up after you've committed. The actual gap exists in the mid-market: services like Mailgun and SendGrid own the enterprise, while Resend and Loops target modern devs, but there's weak coverage for founders who need 50K+ emails monthly at <$50/month with no surprises. A new entrant should obsess over three things: transparent, predictable pricing with zero surprise charges, a dead-simple API that works in <5 minutes, and public deliverability metrics (open rates, bounce rates, spam folder placement) so users trust their mail lands right. The secondary opportunity is for vertically-focused alternatives—e.g., a free transactional email tool specifically for SaaS or e-commerce, bundled with templates or analytics those users actually need.